Internet Gateways (Network Access)
Goals of gateway design:
- switching IP diagrams over heterogeneous sub-networks
- High throughput
- Support for robustness and survivability
The subnet Interface: Collects datagrams from the network and places them on an internal queue. Takes datagrams off an output queue and dispatches them into the network. Manages the address mapping between the IP address and local network address
Routing and dispatch takes datagrams off the interface input queues and dispatches them to the output queue of an appropriate sub-network interface. Uses the routing tables of the gateway. Uses the time-to-live field to ensure packets don’t circulate forever.